Hydrogen-rich syngas upgrading via CO adsorption by amine-functionalized Cu-BTC: the effect of different amines.

Syngas produced from supercritical water gasification typically contain a high amount of CO along with H. In order to improve the quality of syngas, amine-functionalized copper benzene-1,3,5-tricarboxylate (Cu-BTC) was synthesized as an effective adsorbent for selective removal of CO from syngas to increase the concentration of H. The amines used in this study included monoethanolamine (MEA), ethylenediamine (EDA), and polyethyleneimine (PEI). The fundamental physicochemical character of adsorbents, CO adsorption capacity, and CO/H selectivity were analyzed. The physicochemical characterization indicated that the structure of amine-functionalized Cu-BTC was partially damaged, which resulted in a decrease in specific surface area and pore volume. On the other hand, the enlarged pore size was beneficial for the mass transfer of gas in the adsorbent. Among these adsorbents, Cu-BTC/PEI exhibited the maximum CO adsorption capacity of 3.83 mmol/g and the highest CO/H selectivity of 19.74. It was found that the adsorption pressure is the most significant factor for the CO adsorption capacity. Lower temperature and higher pressure were favored for CO adsorption capacity and CO/H selectivity, so physical adsorption by Cu-BTC played a dominant role. Moreover, Cu-BTC/PEI can be well-regenerated with stable adsorption efficiency after five consecutive cycles. These findings suggested that Cu-BTC/PEI could be a promising alternative adsorbent for CO capture from syngas.